Due to the importance of ornamental fishing of silver arowana, as well as, Lago Grande lake as one of the main areas for capturing baby arowanas in Peru, the present study aimed to evaluate the productivity and the biologicalreproductive characteristics of the species in the lake, which is located in the lower basin of the Putumayo River and represents an area preferred by fishermen because the important populations of silver arowana inhabiting it. Analysis of population density, biometrics, sexual maturity, spawning, fecundity, sex ratio, water level of the lake and production of baby arowana were made. The study was developed between March and July of 2012 and to implement the activities of the study was important the participation of the Association of Fishermen "Fronteras Vivas". In general, the population density extrapolated to the lake area was 1.29 fish/ha. Of these, the density of progenitors in the lake was 1.19 fish/ha. Also, male animals had total length, standard length and total weight higher than females and it was observed that the spawning period occurred in synchronization with the start of the growing of the hydrological regime. The average number of oocytes produced by females of silver arowana in the study area was 201 and the sex ratio was equilibrated. Furthermore, the study shows the capacity of production of the lake. In order to this the water lever influenced in the production of baby arowanas. It is important to continue studying the species for regulate the fishing and recover populations.